Characterization of transformed soybean strains expressing GbNPR1 and HrpZpsg12 genes for disease resistance

Abstract

To improve soybean broad-spectrum disease resistance, a bivalent plant expression vector carrying the GbNPR1 and HrpZpsg12 genes with the Bar gene as a selectable marker was constructed and transformed into soybean cultivar ‘Jinong 28’ using an Agrobacterium-mediated method. The results of PCR, Southern blot and SDS-PAGE analyses indicated that the two disease resistance genes, GbNPR1 and HrpZpsg12, and the selectable marker gene, Bar, were successfully integrated into the genome of soybean Jinong 28 and the proteins encoded by the inserted genes were expressed in the transgenic plants. Real-time quantitative PCR results at T2 to T4 revealed that relative expression levels of two disease resistance genes, GbNPR1 and HrpZpsg12 were similar, both highest in leaves, followed by roots, and much lower in stem and matured seed. The relative expression levels of these genes at T3 and T4 generations were similar and much higher than that at T2 generation, implying that transgenic strains were stably inherited to T4 generation. The disease resistance of transgenic strains was significantly increased to moderately resistant to both Phytophthora sojae and Cercospora sojina with artificial inoculation methods. Field evaluation results with artificial infection demonstrated that the T3 and T4 transgenic strains had significantly improved the resistance to both P. sojae and C. sojina when compared with the transformation donor.